Many imaging applications, such as military, biomedical, telescopes, reconnaissance planes, satellites, forward-looking infrared, staring sensor systems, night-vision goggles, and other optic and/or electro-optic detection systems demand simultaneous detection in separate wavelength bands, e.g. in the mid-wave infrared and the long-wave infrared spectral ranges. Traditionally, such dual band imaging has required separate refractive lens systems with separate associated detectors, or reflective systems including multiple mirror reflectors. Reflective systems have suffered from a narrow field of view, thus leading to a preference for refractive systems.
More recently, dual band refractive lens systems configured to simultaneously image light from first and second wavelength bands onto a common focal plane, e.g. at a multi-band detector, have emerged. Such systems, however, tend to include lenses with aspheric surfaces. Manufacturing of aspheric surfaces may require expensive and time consuming diamond point turning (DPT) manufacturing processes and/or additional post polishing.
Therefore, there is a need for a dual band lens system incorporating components that may be efficiently manufactured.